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Question:

The Wheatstone bridge shown in Fig. here, gets balanced when the carbon resistor used as R1 has the colour code (Orange, Red, Brown). The resistors R2 and R4 are 80 and 40 respectively. Assuming that the colour code for the carbon resistors gives their accurate values, the colour code for the carbon resistor used as R3 would be Brown, Blue, Brown, Grey, Black, Brown, Brown, Blue, Black, Red, Green, Brown.

Red, Green, Brown

Brown, Blue, Brown

Grey, Black, Brown

Brown, Blue, Black

Solution:

R1 = 32 x 10 = 320
for wheat stone bridge
R1/R3 = R2/R4
320/R3 = 80/40
R3 = 160